Qtpfsgui

Qtpfsgui is an free software (as in freedom, but also as in beer) application for creating HDR images. It's available for Mac OS X, GNU/Linux and Windows. Aside from the name, which seems to stem from the GUI toolkit it uses (Qt), and pfs (the set of commands it creates the gui for) it looks promising and is definitely a cheaper alternative to get into HDR imaging. I'm looking forward to taking a look at it soon.